Few issues Options

[x_itchy_b_x]

meh, i didn't mean to split hairs.
generally a vacuum leak is a boost leak and vice versa.
I found a hg/kpa calculator
http://www.shender4.com/pressure.htm
-99 kpa is 29.23 Hg and 14.36 psi. so, is that gauge giving you atmospheric pressure?

[devilsden97]

itchy. i didnt get 29.23 hg


i got.


-9.9 Kpa = -74.2563118 mmHg = -.0742563118 Hg = -1.4358737 PSI (all assumed at 0°C)
-99 kpa = -742.563118 mmHg = -.742563118 Hg = -14.358737 PSI (all assumed at 0°C)


to get 20hg

20hg = 26.6644 Kpa (again assuming at 0°C)


edit: moved my decimal incorrectly

http://online.unitconverterpro.com/unit-co...a/pressure.html
---------------------------------------------------------------------------------------------------------------------

another site:

-9.9 kpa = -74.2561065876959 mmHg (at 0°C) = -.0742561065876959 Hg = -1.4358736035269995 PSI
-99 kpa = -742.561065876959 mmHg (at 0°C) = -.742561065876959 Hg = -14.358736035269995 PSI

btw i used: http://www.digitaldutch.com/unitconverter/


edit: adjusted from brians post below.

This post has been edited by devilsden97: May 7, 2007 - 10:35 PM

[brianforster]

it would be important to note here that the gauge is reading -9.9, not -99, there is a decimal just like when you read boost (i assume you have yours set to read in PSI, like mine, jeff)

This post has been edited by brianforster: May 7, 2007 - 10:26 PM

[devilsden97]

so move the decimal over one place to the right.

This post has been edited by devilsden97: May 7, 2007 - 10:25 PM

[alltracman78]

alltracman78.... i think what itchy was trying to say is that anything that leaks vac at idle will leak boost when you are boosting. so if the vac line for your powersteering is leaking at idle, it will also leak at boost. thats why we consider boost/vac least to mean pretty much the same thing.

meh, i didn't mean to split hairs.
generally a vacuum leak is a boost leak and vice versa

I was trying to split hairs.
That's what you have to do when you're trying to figure out a difficult problem.
While a vacuum leak generally will also be a boost leak, it's not ALWAYS so.
That's why I said what I said....

I found a hg/kpa calculator
http://www.shender4.com/pressure.htm
-99 kpa is 29.23 Hg and 14.36 psi. so, is that gauge giving you atmospheric pressure?

It's actually negative 29.23 in/hg and negative 14.36 PSI.
Which means while it's the correct conversion, it's not the right reading.
There is no way his engine is pulling 29 in/hg......


So bottom line, the first thing that needs to be done is get a correct vacuum reading.
Otherwise we're just pissing in the wind as they say.

[alltracman78]

it would be important to note here that the gauge is reading -9.9, not -99, there is a decimal just like when you read boost (i assume you have yours set to read in PSI, like mine, jeff)

that wouldn't make much sense though....

-9.9 KPA is -2.9xx in/hg.
Which isn't even close to what an engine should read.
If you're only pulling that much vacuum, your engine wont' even be running most likely.
:shrug:
dunno, I don't have the gauge in front of me, nor am I a physics/math major.

-99 makes sense because vacuum gauges normally read down to 30 in/hg [negative].
If it is reading that, it just means the gauge is reading [incorrectly] to it's lowest reading.

[brianforster]

it would be important to note here that the gauge is reading -9.9, not -99, there is a decimal just like when you read boost (i assume you have yours set to read in PSI, like mine, jeff)

that wouldn't make much sense though....

-9.9 KPA is -2.9xx in/hg.
Which isn't even close to what an engine should read.
If you're only pulling that much vacuum, your engine wont' even be running most likely.
:shrug:
dunno, I don't have the gauge in front of me, nor am I a physics/math major.

-99 makes sense because vacuum gauges normally read down to 30 in/hg [negative].
If it is reading that, it just means the gauge is reading [incorrectly] to it's lowest reading.

thats because when you change the greddy to read in PSI, the - is no longer reading in KPA, im not sure what it reads in, ive been trying to find out through google but have had no such luck.

it somehow is reading in negative PSI, because -9.9 psi is -20.1589183 hg

This post has been edited by brianforster: May 7, 2007 - 10:35 PM

[devilsden97]

itchy and Brian, how did u get SUCH different numbers for mmHg/Hg as Stevenson, and I. We both agree that the numbers we have are correct. (i have since done it out on my own, and obtained the same answer as the converter)


im betting the ranch on a faulty gauge/poor connection.

Good luck Jeff.

edit:
i got: -9.9 PSI = -511.979225 mmHg or -.511979225 Hg


WTF is going on.

This post has been edited by devilsden97: May 7, 2007 - 10:41 PM

[brianforster]

for every 1 number that our gauge is reading (-99 vs -98) there is a 0.20 in/hg difference.

so the original problem (sometimes it says 95 sometimes it says 99) is not a big deal cause thats a difference of .8 in/hg.

its just easier to panic when you have a digital readout versus a needle on your gauge.

[brianforster]

itchy and Brian, how did u get SUCH different numbers for mmHg/Hg as Stevenson, and I. We both agree that the numbers we have are correct. (i have since done it out on my own, and obtained the same answer as the converter)


im betting the ranch on a faulty gauge/poor connection.

Good luck Jeff.

edit:
i got: -9.9 PSI = -511.979225 mmHg or -.511979225 Hg


WTF is going on.

-511.979225 millimeters of mercury = -20.1589731 inches of mercury

i think when most of us say HG we mean inches of mercury because thats what boost gauges read in, and you and stevenson were not calculating inches of mercury.

This post has been edited by brianforster: May 7, 2007 - 10:50 PM

[devilsden97]

^really?

edit:

-511.979225 mmHg = -20.156662401553305 inHg...


well ill be.

wow so units DO matter.


edit: when u said "Hg" brian i was assuming you ment, meters of Hg, like my conversion was. not Inches.

This post has been edited by devilsden97: May 7, 2007 - 10:52 PM

[alltracman78]

it would be important to note here that the gauge is reading -9.9, not -99, there is a decimal just like when you read boost (i assume you have yours set to read in PSI, like mine, jeff)

that wouldn't make much sense though....

-9.9 KPA is -2.9xx in/hg.
Which isn't even close to what an engine should read.
If you're only pulling that much vacuum, your engine wont' even be running most likely.
:shrug:
dunno, I don't have the gauge in front of me, nor am I a physics/math major.

-99 makes sense because vacuum gauges normally read down to 30 in/hg [negative].
If it is reading that, it just means the gauge is reading [incorrectly] to it's lowest reading.

thats because when you change the greddy to read in PSI, the - is no longer reading in KPA, im not sure what it reads in, ive been trying to find out through google but have had no such luck.

it somehow is reading in negative PSI, because -9.9 psi is -20.1589183 hg

Ah, that makes sense.

It would help if I had one of these in front of me.

[brianforster]

i understand, it was a misunderstanding, but now that its cleared up we can all rest easy knowing that each tick on our readout (atleast on the greddy gauge) isnt a big deal cause its pretty much a fluctuation which we wouldn't even notice on the needle.

[Defgeph]

Brian, I'm wrong. I think your on the money with -9.9 psi. From what I've seen in that converter it makes sense. I could swear I heard or read somewhere that it reads negative pressure in KPA

Jeremy, I can't wait to hook up with ya man. Another gauge sounds great dude

[lagos]

greddy really did a crappy job with this thing, huh?

[brianforster]

not crappy , just lazy, its the same solenoid as the type S, and the tuning capabilities are phenomenal, its just the display of boost/vac i think was a little rushed, if you leave it in KPA it makes sense, but if you try to turn it to psi you get confused because it starts giving you a - psi reading.

[Defgeph]

I'm going to swap in some new plugs (bkr7e) this weekend and check out all of my ignition parts make sure they look ok.

Also going to check out my Autometer. Find out if its the gauge or the line leaking. I'll be replacing the Vac line under the TB as well.

Anything else I should look for ?

Thanks guys

[alltracman78]

Spray starting fluid around any suspected leaks.
If your idle raises, you have a leak.
Be careful though, it's really flammable.

[Defgeph]

Spray starting fluid around any suspected leaks.
If your idle raises, you have a leak.
Be careful though, it's really flammable.

Thanks Jeremy! I got a box with your name on it brother.

[Defgeph]

Update:

I checked the boost gauge as suggested by Manny. It turns out the nylon line connected the the boost gauge was leaking. I always hated this nylon line.

So I replaced it with a rubber hose. The vac reading is now normal on the Autometer. The Greddy on the other hand is still fluctuating. Funny huh?

I did a spark plug change, Still ran alittle rough at times(idle after boosting) but doesnt stall anymore. So I think after a regap of the plugs I should be all set.

I just dont get way the Greddy's vac readings are all over the place.

But thanks for the help guys, it's running alittle better now.

DEF